Floyd Mayweather's Son -- 14-Year-Old Blasts Boxer ... He's a Coward

Floyd Mayweather's 14-year-old son is lashing out against his father -- claiming he's a coward for refusing to admit he beat the crap out of his mother Josie Harris back in 2010.

Koraun Mayweather spoke with USA Today with his mother's permission and described what happened in September 2010 ... when he witnessed Floyd punching and kicking Josie ... so he snuck out of his Vegas home and alerted security, who then summoned police.

"[My dad] said to lock my door and stay in my room. I sat there and thought about what I was going to do next ... just for like a minute."

Koraun said he eventually "ran back out my bathroom and then hopped over the gate and went to the main entrance gate. I just told [the guard] that my mom was getting hurt and to call the ambulance and the police."

Eventually cops arrived ... and Koraun told investigators what he saw. Mayweather pled guilty to a reduced battery domestic violence charge and was sentenced to 90 days behind bars. Koraun says he's upset that his father never apologized for the incident publicly.

Koraun also says he still spends time with his father -- but he's less than enthusiastic about it.

"We just hang out. We either watch a movie or something, or go bowling. I find [boxing] boring. It is just like how people sit in the ring and fight for 12 rounds and it gets boring after a while."